i) A researcher measured and recorded a dataset on 13 batches of cement with three predictor variables were selected randomly. Possible selected models were constructed, and the following table gives the selection criterion for each model. ii) iii) Model 1 2 3 4 5 6 7 Variables X X X3 X1, X2 X1, X3 X2, X3 X, X2, X3 R-Squared (Adj) Mallow's Cp 138.7 142.5 2.7 5.5 3.0 3.0 5.0 0.645 0.636 0.974 0.967 0.976 0.976 0.974 The total sum of squares is 2715.8. Find the mean of square error for each model. Using all the criterion above, determine the best set of variables that should be used. Write down the estimated model. Explain other criteria for model selection that can be used in this study.